Towards an integrated Jurassic biostratigraphy for eastern Greenland

The thick and relatively complete Jurassic succession of eastern Greenland provides a unique biostratigraphic record for the North Atlantic region. The main biostratigraphic control for the succession has been provided by molluscs, especially ammonites and to a lesser extent by bivalves and belemnites. For example the late John Callomon and colleagues recognised 86 boreal ammonite-bearing horizons in the Mid to Late Jurassic, allowing an average duration of less than 300,000 years for each interval. Palynological and micropalaeontological schemes for Greenland remain less comprehensive, but continue to improve. Offshore in the North Sea a precision of about 700,000 and 1,000,000 years can be achieved by palynomorphs and micropalaeontology respectively. The Greenland succession provides an important opportunity to integrate the micropalaeontology and palynology into the well-documented and more detailed ammonite macrofaunal succession. Collecting directly from outcrop often achieves better and more accurate results than from recovered chippings from cored samples. Seldom are continuous cores available for analysis from mudstone successions and only rarely are macrofossils such as ammonites recovered.

Reliance upon any single organism group can only provide an incomplete biostratigraphic picture, especially when one moves from marine to non-marine environments. This is particularly so for the Early Jurassic rocks of eastern Greenland. Integrated data is very important here as no single biostratigraphic group can be used successfully throughout, and there are only three significant ammonite faunas during this period.

CASP field-work from 1990 to 2012 has resulted in the collection of much biostratigraphic material which has been documented using Stratabugs. In this article published data are summarised together with previously unpublished data in table form. The integrated charts have detailed columns for ammonite biozones and horizons, palynological and microfossil biozones. More limited information is available on belemnites, bivalves and macroflora. This integrated biostratigraphy for eastern Greenland is of importance for the offshore oil-industry in the northern North Atlantic and Barents Shelf as well as to students of the Jurassic outcrops of Scotland, onshore Norway and Svalbard.